<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<h1 id="box"></h1>
<script>
    var ss = document.getElementById('box');

    function ff(){
        debugger;
    }
    setInterval(ff,500)

    ss.innerHTML = '大家好'

</script>


</body>
</html>